How do these organisms interact with one another and with the nonliving parts of the environment? 2. What might happen if the zebras were removed?

Ecology Principles of Ecology Organisms and Their Environment
Unit Overview – pages 32-33

Section 2.1 Summary – pages 35 - 45
Sharing the World What affects the environment also affects you. Understanding what affects the environment is important because it is where you live. Section 2.1 Summary – pages

What is ecology? Ecology: the study of interactions that take place between organisms and their environment. Section 2.1 Summary – pages

The Biosphere Biosphere: portion of Earth that supports living things. It extends from high in the atmosphere to the Earth’s crust. Section 2.1 Summary – pages

The Biosphere Although it is thin, the biosphere supports a diverse group of organisms in a wide range of climates. Living things are affected by both the physical or nonliving environment and by other living things. Section 2.1 Summary – pages

The nonliving environment: Abiotic factors Abiotic factors: the nonliving parts of an organism’s environment Examples of abiotic factors include air currents, temperature, moisture, light, and soil. Section 2.1 Summary – pages

The nonliving environment: Abiotic factors Ecology includes the study of features of the environment that are not living because these features are part of an organism’s life. Abiotic factors have obvious effects on living things and often determine which species survive in a particular environment. Section 2.1 Summary – pages

The living environment: Biotic factors A key consideration of ecology is that living organisms affect other living organisms. Biotic factors: all the living organisms that inhabit an environment All organisms depend on others directly or indirectly for food, shelter, reproduction or protection. Section 2.1 Summary – pages

Levels of Organization Ecologists study individual organisms, interactions among organisms of the same species, interactions among organisms of different species, as well as the effects of abiotic factors on interacting species. Ecologists have organized the living world into levels—the organism by itself, populations, communities, and ecosystems. Section 2.1 Summary – pages

Organism An individual living thing that is made of cells, uses energy, reproduces, responds, grows, and develops. Section 2.1 Summary – pages

Interactions within populations Population: a group of organisms, all of the same species, which interbreed and live in the same area at the same time. Section 2.1 Summary – pages

Interactions within populations Members of the same population may compete with each other for food, water, mates, or other resources. Competition can occur whether resources are in short supply or not. Section 2.1 Summary – pages

Interactions within communities Just as a population is made up of individuals, several different populations make up a biological community. Section 2.1 Summary – pages

Interactions within communities Biological community: made up of interacting populations in a certain area at a certain time. Section 2.1 Summary – pages

Interactions within communities A change in one population in a community may cause changes in the other populations. Some of these changes can be minor, such as when a small increase in the number of individuals of one population causes a small decrease in the size of another population. Section 2.1 Summary – pages

Interactions within communities Other changes might be more extreme, as when the size of one population grows so large it begins affecting the food supply for another species in the community. Section 2.1 Summary – pages

Ecosystem Populations of plants and animals that interact with each other in a given area and with the abiotic components of that area. Section 2.1 Summary – pages

Biotic and abiotic factors form ecosystems Ecosystem: made up of interacting populations in a biological community and the community’s abiotic factors. There are two major kinds of ecosystems—terrestrial ecosystems and aquatic ecosystems. Section 2.1 Summary – pages

Biotic and abiotic factors form ecosystems Table 2.1 Examples of Ecosystems Terrestial ecosystems are those located on land. Aquatic Ecosystems Other Sites for Ecosystems Terrestrial Ecosystems Forest Old farm field Meadow Yard Garden plot Empty lot Compost heap Volcano site Rotting log Freshwater Pond Lake Stream Estuary Salt water (marine) Ocean Aquarium Human body Skin Intestine Mouth Buildings Mold in walls, floors, or basement Ventilation systems Bathrooms Food Any moldy food Refrigerator Section 2.1 Summary – pages

Biotic and abiotic factors form ecosystems Table 2.1 Examples of Ecosystems Aquatic ecosystems occur in both fresh- and saltwater forms. Aquatic Ecosystems Other Sites for Ecosystems Terrestrial Ecosystems Forest Old farm field Meadow Yard Garden plot Empty lot Compost heap Volcano site Rotting log Freshwater Pond Lake Stream Estuary Salt water (marine) Ocean Aquarium Human body Skin Intestine Mouth Buildings Mold in walls, floors, or basement Ventilation systems Bathrooms Food Any moldy food Refrigerator Section 2.1 Summary – pages

Biotic and abiotic factors form ecosystems Freshwater ecosystems include ponds, lakes, and streams. Section 2.1 Summary – pages

Biotic and abiotic factors form ecosystems Saltwater ecosystems, also called marine ecosystems, make up approximately 70 percent of Earth’s surface. Section 2.1 Summary – pages

Organisms in Ecosystems Habitat: the place where an organism lives out its life. Section 2.1 Summary – pages

Organisms in Ecosystems Habitats can change, and even disappear. Habitats can change due to both natural and human causes. Section 2.1 Summary – pages

Niche Although several species may share a habitat, the food, shelter, and other essential resources of that habitat are often used in different ways. Niche: the role or position a species has in its environment—how it meets its specific needs for food and shelter, how and where it survives, and where it reproduces in its environment. Section 2.1 Summary – pages

Niche A species’ niche, therefore, includes all its interactions with the biotic and abiotic parts of its habitat. It is thought that two species can’t exist for long in the same community if their niches are the same. Section 2.1 Summary – pages

Symbiosis Symbiosis: the relationship in which there is a close and permanent association between organisms of different species Symbiosis means living together. Three kinds of symbiosis are recognized: mutualism, commensalism, and parasitism. Section 2.1 Summary – pages

Mutualism Mutualism: a symbiotic relationship in which both species benefit Section 2.1 Summary – pages

Commensalism Commensalism: a symbiotic relationship in which one species benefits and the other species is neither harmed nor benefited. Section 2.1 Summary – pages

Parasitism Some interactions are harmful to one species, yet beneficial to another. Parasitism: a symbiotic relationship in which a member of one species derives benefit at the expense of another species (the host) Section 2.1 Summary – pages

Parasitism Parasites have evolved in such a way that they harm, but usually do not kill the host species. Section 2.1 Summary – pages

What is the source of all energy in this ecosystem. 2
What is the source of all energy in this ecosystem? 2. What path does this energy take to get to the hawk?

Ecology Principles of Ecology Nutrition and Energy Flow
Unit Overview – pages 32-33

How Organisms Obtain Energy One of the most important characteristics of a species’ niche is how it obtains energy. Ecologists trace the flow of energy through communities to discover nutritional relationships between organisms. Section 2.2 Summary – pages

The producers: Autotrophs The ultimate source of the energy for life is the sun. Plants use the sun’s energy to manufacture food in a process called photosynthesis. Section 2.2 Summary – pages

The producers: Autotrophs Autotroph: an organism that uses light energy or energy stored in chemical compounds to make energy-rich compounds Other organisms in the biosphere depend on autotrophs for nutrients and energy. These dependent organisms are called consumers. Section 2.2 Summary – pages

The consumers: Heterotrophs Heterotroph: an organism that cannot make its own food and feeds on other organisms Heterotrophs include organisms that feed only on autotrophs, organisms that feed only on other heterotrophs, and organisms that feed on both autotrophs and heterotrophs. Section 2.2 Summary – pages

The consumers: Heterotrophs Heterotrophs display a variety of feeding relationships. A heterotroph that feeds only on plants is an herbivore. Section 2.2 Summary – pages

The consumers: Heterotrophs Some heterotrophs eat other heterotrophs. Animals that kill and eat only other animals are carnivores. Section 2.2 Summary – pages

The consumers: Heterotrophs Scavengers eat animals that have already died. Section 2.2 Summary – pages

The consumers: Heterotrophs Some organisms, such as bacteria and fungi, are decomposers. Section 2.2 Summary – pages

The consumers: Heterotrophs Decomposers break down the complex compounds of dead and decaying plants and animals into simpler molecules that can be more easily absorbed. Omnivores eat both plants and animals. Section 2.2 Summary – pages

Flow of Matter and Energy in Ecosystems Autotrophs Third-order heterotrophs Second-order heterotrophs First-order heterotrophs Decomposers Section 2.2 Summary – pages

Food chains: Pathways for matter and energy Food chain: a simple model that scientists use to show how matter and energy move through an ecosystem. In a food chain, nutrients and energy move from autotrophs to heterotrophs and, eventually, to decomposers. Section 2.2 Summary – pages

Food chains: Pathways for matter and energy A food chain is drawn using arrows to indicate the direction in which energy is transferred from one organism to the next. berries → mice → black bear Section 2.2 Summary – pages

Food chains: Pathways for matter and energy Most food chains consist of two, three, or four transfers. The amount of energy remaining in the final transfer is only a portion of what was available at the first transfer. A portion of the energy is given off as heat at each transfer. Section 2.2 Summary – pages

Trophic levels represent links in the chain Trophic level: a feeding step in a food chain that is represented by an organism in the passage of energy and materials. A first order heterotroph is an organism that feeds on plants, such as a grasshopper. Section 2.2 Summary – pages

Trophic levels represent links in the chain A second order heterotroph is an organism that feeds on a first order heterotroph. A food chain represents only one possible route for the transfer of matter and energy through an ecosystem. Section 2.2 Summary – pages

Food Chains Quaternary consumer Carnivore Tertiary consumer
Carnivore/Omnivore Secondary consumer Carnivore/Omnivore Herbivore Primary consumer Producer Producer

Food webs Ecologists interested in energy flow in an ecosystem may set up experiments with as many organisms in the community as they can. Food web: a model that shows all the possible feeding relationships at each trophic level in a community. Section 2.2 Summary – pages

Food Webs

Energy and trophic levels: Ecological pyramids Ecological pyramid: a model that shows the amount of energy available at each feeding level in an ecosystem. The base of the ecological pyramid represents the autotrophs, or first trophic level. Higher trophic levels are layered on top of one another. Section 2.2 Summary – pages

Energy and trophic levels: Ecological pyramids Pyramid of Energy Heat 0.1% Consumers The pyramid of energy illustrates that the amount of available energy decreases at each succeeding trophic level. Heat 1% Consumers 10% Consumers Heat 100% Producers Heat Parasites, scavengers, and decomposers feed at each level. Section 2.2 Summary – pages

Energy and trophic levels: Ecological pyramids The total energy transfer from one trophic level to the next is only about ten percent because organisms fail to capture and eat all the food energy available at the trophic level below them. Section 2.2 Summary – pages

Energy and trophic levels: Ecological pyramids Some of the energy transferred at each successive trophic level enters the environment as heat, but the total amount of energy remains the same. Section 2.2 Summary – pages

Energy and trophic levels: Ecological pyramids Pyramid of Numbers A pyramid of numbers shows that population sizes decrease at each higher trophic level. Fox (1) Birds (25) Grasshoppers (250) Grasses (3000) Section 2.2 Summary – pages

Energy and trophic levels: Ecological pyramids Biomass: the total weight of living matter at each trophic level. A pyramid of biomass represents the total weight of living material available at each trophic level. Pyramid of Biomass 1 kilogram of human tissue 10 kilograms of beef 100 kilograms of grain Section 2.2 Summary – pages

Cycles in Nature Matter, in the form of nutrients, moves through, or is part of, all organisms at each trophic level. But matter is cycled and is not replenished like the energy from sunlight. There is a finite amount of matter. Section 2.2 Summary – pages

The Water Cycle Water cycle: the continuous movement of water from the ocean to the atmosphere to the land and back to the ocean. Evaporation: the change of a substance from a liquid to a gas. Water continually evaporates from the Earth’s oceans, lakes, streams, and soil, but the majority evaporates from the oceans.

The Water Cycle Condensation: the change of state from a gas to a liquid. Water vapor forms water droplets on dust particles which then form clouds in which the droplets collide to create larger, heavier drops that then fall from the clouds as rain. Precipitation: any form of water that falls to the Earth’s surface from the clouds, and includes rain, snow, sleet, and hail.

The water cycle

The Carbon Cycle Carbon cycle: the movement of carbon from the nonliving environment into living things and back Carbon is the essential component of proteins, fats, and carbohydrates, which make up all organisms.

The Carbon Cycle

The Carbon Cycle Carbon exists in air, water, and living organisms.
Producers convert carbon dioxide in the atmosphere into carbohydrates during photosynthesis. Consumers obtain carbon from the carbohydrates in the producers they eat.

The Carbon Cycle During cellular respiration, some of the carbon is released back into the atmosphere as carbon dioxide.

The Carbon Cycle Carbon stored in the bodies of organisms as fat, oils, or other molecules, may be released into the soil or air when the organisms dies. These molecules may form deposits of coal, oil, or natural gas, which are known as fossil fuels. Fossil fuels store carbon left over from bodies of organisms that dies millions of years ago.

The Nitrogen Cycle Nitrogen cycle: the process in which nitrogen circulates among the air, soil, water, plants, and animals in an ecosystem. All organisms need nitrogen to build proteins, which are used to build new cells. Nitrogen makes up 78 percent of the gases in the atmosphere.

The Nitrogen Cycle Nitrogen must be altered, or fixed, before organisms can use it. Only a few species of bacteria can fix atmospheric nitrogen into chemical compounds that can be used by other organisms. These bacteria are known as “nitrogen-fixing” bacteria.

The Nitrogen Cycle Nitrogen-fixing bacteria: bacteria that convert atmospheric nitrogen into ammonia. These bacteria live within the roots of plants called legumes, which include beans, peas, and clover. The bacteria use sugar provided by the legumes to produce nitrogen containing compounds such as nitrates. Excess nitrogen fixed by the bacteria is released into the soil.

The Nitrogen Cycle

Decomposers and the Nitrogen Cycle
Nitrogen stored within the bodies of living things is returned to the nitrogen cycle once those organisms die. Decomposers break down decaying plants and animals, as well as plant and animal wastes. After decomposers return nitrogen to the soil, bacteria transform a small amount of the nitrogen into nitrogen gas, which then returns to the atmosphere to complete the nitrogen cycle.

The Phosphorus Cycle Phosphorus is an element that is part of many molecules that make up the cells of living organisms. Plants get the phosphorus they need from soil and water, while animals get their phosphorus by eating plants or other animals that have eaten plants.

The Phosphorus Cycle Phosphorus cycle: the cyclic movement of phosphorus in different chemical forms from the environment to organisms and then back to the environment.

The Phosphorus Cycle

The Phosphorus Cycle Phosphorus may enter soil and water when rocks erode. Small amounts of phosphorus dissolve as phosphate, which moves into the soil. Plants absorb phosphates in the soil through their roots. Some phosphorus washes off the land and ends up in the ocean where they sink to the bottom and accumulate as sediment.

How do these organisms interact with one another and with the nonliving parts of the environment? 2. What might happen if the zebras were removed?

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How do these organisms interact with one another and with the nonliving parts of the environment? 2. What might happen if the zebras were removed?

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